Field of the Invention
The present disclosure relates to a liquid discharge head that discharges liquid.
Description of the Related Art
A liquid discharge head that discharges liquid is typically mounted in a liquid discharge apparatus that records an image on a record medium by discharging liquid such as ink. As a mechanism that discharges liquid from the liquid discharge head, a liquid discharge head that employs a pressure chamber that is capable being contracted by a piezoelectric transducer is known. According to the mechanism, the pressure chamber can be contracted and expanded by bending, with a deformed piezoelectric transducer to which a voltage has been applied, a diaphragm that forms a wall of the pressure chamber. With the pressure generated with the above, the liquid inside the pressure chamber is discharged through a discharge opening that is formed at one end of the pressure chamber. A liquid supply passage that supplies liquid is connected to the pressure chamber. A plurality of liquid supply passages are connected to a common liquid chamber, and liquid is supplied from the common liquid chamber.
In recent years, a liquid discharge apparatus that is capable of high-speed plotting is in need. One of such liquid discharge apparatuses achieves high-speed plotting and includes a line head in which discharge openings are arranged in a two-dimensional manner at a high density. In order to perform high-speed plotting, the discharge period of each pressure chamber needs to be short. By reducing the volume of the liquid related to the discharge, the compliance of the fluid can be reduced and the natural frequency of the pressure chamber can be increased.
PCT Japanese Translation Patent Publication No. 2012-532772 discloses a liquid discharge head in which liquid is supplied from a side that is opposite the discharge openings with respect to the diaphragms. The liquid discharge head includes an element substrate, a liquid supply substrate that is stacked on the element substrate, and a photosensitive resin layer with which the element substrate and the liquid supply substrate are adhered to each other. Liquid inflow through-holes penetrate the element substrate, the photosensitive resin layer, and the liquid supply substrate. The element substrate includes pressure chambers that include discharge openings that discharge liquid, liquid supply passages, one end of which is connected to the corresponding pressure chamber and the other end of which is connected to the corresponding liquid inflow through-hole, diaphragms that form surfaces that opposes the discharge openings of the pressure chambers, and piezoelectric transducers that applies vibration to the diaphragms. The liquid that has been supplied through the liquid inflow through-holes passes through the liquid supply passages and is supplied to the pressure chambers. Since the liquid inflow through-holes are provided on the opposite side of the discharge opening with respect to the diaphragm, the distance between the diaphragm and the discharge opening can be made short. Accordingly, the volume of the fluid can be reduced and the response frequency can be increased. The photosensitive resin layer is formed of a photosensitive photoresist SU-8 (MicroChem Corp.). Accordingly, the liquid inflow through-holes can be formed in the photosensitive resin layer by patterning.
Since the photosensitive resin layer includes the liquid inflow through-holes into which liquid flows; accordingly, by being in contact with the liquid, the photosensitive resin layer may swell. The back surface of the surface on the photosensitive resin layer side of the diaphragm is the liquid supply passage and the diaphragm is not restricted on the liquid supply passage side. Accordingly, due to swelling of the photosensitive resin layer, the diaphragm may be pushed by the photosensitive resin layer and may deform towards the liquid supply passage. The diaphragm is formed thin so that the diaphragm greatly deforms the pressure chamber, and has a thickness of 2 μm or under, for example. Due to swelling of the photosensitive resin layer, the diaphragm that has been pressed may be deformed so as to reduce the width of the liquid supply passage and, further, may be damaged.